Compression operated fuel injector pump



April 3, 1956 J. DICKSON ETAL 2,740,567

COMPRESSION OPERATED FUEL INJECTOR PUMP Filed April 4, 1952 2Sheets-Sheet l 3nventors V II (/7 9% 92 8,. z raz z z 'fy (IttornegsApril .3, 1956 J. DICKSON ETAL 2,740,667

COMPRESSION OPERATED FUEL INJECTOR PUMP Filed April 4, 1952 2Sheets-Sheet 2 5 C AN h a l Iinventors ornegs United States Patent2,740,667 COMPRESSION OPERATED FUEL INJECTOR PUMP John Dickson,Huntington Woods, and Kenneth L. Hulsing, Plymouth, Mich., assignors toGeneral Motors Corporation, Detroit, Mich., a corporation of DelawareApplication April 4, 1952, Serial No. 280,624 20 Claims. (Cl. 299-107.2)

This invention relates to fuel injector pumps for internal combustionengines, and particularly to such pumps as are automatically operable bythe compression pressures developed in the engine.

One of the principal objects of the invention is to provide improvementsin such compression operated fuel injector pumps wherein the movement ofthe reciprocating mass in response to said engine pressures may beadjustably retarded to vary the timing of the fuel injection. This isaccomplished in accordance with the present invention by providing thecompression pressure actuated stroke of the reciprocating mass with aperiod of free travel relative to a stationary plunger member, theamount of which free travel may be adjustably varied during pumpoperation by means for effecting longitudinal movement of the plungermember independently of the reciprocating mass.

A further object of the invention resides in an improved design ofpumping cylinder comprising an open-ended sleeve or bushing into one endof which is pressed an inwardly presenting cup Whose side walls tend toexpand under pumping pressure and effect a seal with the walls of thebushing.

Another object of the invention relates to an improved seal assemblybetween relatively reciprocating surfaces of the pump, comprising a softrubber ring held under axial compression and provided with a pluralityof axially spaced apart resilient metal rings which are recessed in thesealing face of the rubber, the rubber between the rings serving toblock communication between the ring gaps.

A still further object of the invention is to prevent excessive backpressure developing behind the pump piston as the result of blow-by fromthe engine combustion chamber. In accordance with this aspect of theinvention the piston is provided with conventional piston type rings,the grooves for which have their outer side walls scalloped or notched.

Illustrative embodiments for carrying out these and other objects of theinvention will now be described, having reference to the drawingswherein:

Figure 1 is a longitudinal cross section of a fuel injector pumpconstructed in accordance with the invention and shown inserted in anopening therefor in an engine cylinder head, portions of the latterbeing broken away.

Figure 2 is an enlarged diagrammatic developed view of the pump plungerof Figure 1, with the cooperating cylinder ports and control edgessuperimposed thereon in broken outline to show their relative positionsduring operation of the pump.

Figures 3, 4 and 5 are views similar to Figure 2 showing respectivemodifications of the invention.

Figure 6 is a fragmentary view similar to Figure l but taken in a planeat right angles thereto and showing features of the plunger and bushingcorresponding to the modification of Figure 3.

As best illustrated in Figure 1, one form of this unit fuel injectionpump comprises a hollow cylindrical pump body 1 insertable into a bore 3extending from the inner face 5 to the outer face 7 of a cylinder head 9of an internal combustion engine of a compression ignition type. Thepump body 1 is provided at its outer end with an external mountingflange 11 secured by cap screws 13 to the outer face 7 of the cylinderhead 9, and the inner face 5 of this cylinder head forms the outer wallof the combustion chamber for the internal combustion engine. Anexternal groove is shown provided adjacent the inner end of the pumpbody 1 and a compressible packing ring 15 of soft rubber or equivalentmaterial is placed in sealing engagement between the bottom and endwalls of this groove and the wall of the cylinder head bore 3. The pumpbody 1 intermediate the mounting flange 11 and sealing ring 15 is ofsmaller outside diameter than the cylinder head bore 3 and forms anannular outer fuel receiving space 17. A fuel inlet passage 19 and afuel return passage 21 provided in the cylinder head connect this space17 to a transfer pump or other source of fuel under pressure, not shown.The cylindrical wall of the pump body 1 is provided with a combined fuelinlet and outlet port 23 having an enlargement 25 at its outer end inwhich a fuel filter 27 is press fitted or otherwise secured to excludeforeign particles from entering the pump body with the fuel. The pumpbody has an axial bore 28 terminating upwardly in successivecounterbores 29, 30 and 31.

Guided for longitudinal reciprocation in the pump body is an open endedbushing 33 which forms a movable pump cylinder. This bushing is providedwith upper and lower end portions 35 and 37 and an intermediate portionforming an external flange 39. The lower portion 35 of the bushing 33has a close sliding fit in the body bore 28, and the flange 39 has aloose clearance fit in the body counterbore 29. Between the flange 39and the body counterbore 30 is an annular inner fuel receiving space 40.

The lower end face of the pump body 1 is provided with a counterbore,and a compressible sealing ring 41 of synthetic rubber is pressed intothis counterbore and has two inspringing metallic packing rings 43imbedded in the internal surface of the ring 41 which snugly engage thecylindrical outer periphery of the portion 37 of the bushing 33 toprevent leakage of fluid at this point between the bushing and pumpbody 1. The ring 41 is preferably made of neoprene and is held in axialcom pression by a ring 45 which, in turn, is held in abutment with thelower end face of the pump body by a compression spring 47.

A hollow piston 49 is threaded on the lower end portion of the bushing33 and the spring 47 is placed between the ring 45 and a washer 51engaging an external shoulder on the piston. It will be evident thatwith this arrangement the spring 47 tends to hold the bushing flange 39in contact with the bottom of the pump body counterbore 29. The pistonis provided with external grooves 53 in which outspringing metallicpacking rings 55 are placed to effect a seal against loss of enginecompression pressure and escape of combustion gases between the pistonand a reduced diameter portion 57 of the cylinder head bore 3. The lowerwalls of each of the piston grooves 53 are provided withcircumferentially spaced upwardly open slots 59 extending the full depthof the grooves to prevent a build-up of air and gas pressure above thepiston resulting from such leakage as occurs past the packing rings 55.

A small diameter axial bore is provided in the piston 49 adjacent thelower end or working face 60 of the piston and a larger diameter axialbore is located inwardly of the smaller bore to form a shoulder 61 onwhich an external flange 63 of a fuel spray nozzle 65 is seated. The tipof the spray nozzle 65 is shown projecting through the piston bore andthe tip is provided with fuel spray holes 66 opening into the lower endof a small diameter axial passage 67 in the nozzle. A larger diameteraxial counterbore 68 is provided in the nozzle upwardly adjacent thesmall diameter axial passage 67 to form a shoulder on which a lowerspring seat 69 is seated. The lower face of this seat 69 is providedwith radial grooves 70 connecting the counterbore 69 with the axialpassage 67. A hollow cylindrical valve seat 71 having an axial passage72 is seated on the upper face of the spray nozzle, and a spacer 73separates the adjacent end faces of the valve seat 71 and the bushing33. A downwardly opening check valve 74 is urged upwardly against theseat 71 by a spring 75 compressed between this valve and the lowerspring seat 69, and a counterbore is provided in the upper end face ofthe seat 71 in which a second downwardly opening check valve in the formof a disc 77 is arranged for limited axial travel. The disc 77 has aplurality of notches 78 in its outer periphery, through which fuel mayenter the passage 72 in the valve seat 71, but which are closableagainst flow in the opposite direction by the lower end face of thespacer 73.

The spacer is provided with a fuel discharge passage 79 extending fromthe center of its lower face to an annular groove 81 in the upper faceof the spacer 73, and a longitudinal tip passage 83 is provided in thewall of the bushing lower portion 37 for connecting the annular groove81 to a radial tip port 85 provided in the bore 84 of the bushing. Afuel relief port 86 is provided in the wall of the bushing diametricallyopposite the tip port 85 and registers during the full stroke of thepump with a duct 80 extending through the wall of the body 1 to the fuelspace 17.

Above these tip and relief" ports 85 and 86 are one or more fill ports87 (two being shown) which extend through the flange 39 and connect theinner fuel receiving space 40 with the bore 84 of the bushing. Leakagereturn ports 88 are also shown which extend outwardly through the wallof the upper bushing portion 35 from an internal groove 89 formed in thebore 84. As a predetermined distance below the tip and relief ports 85and 86 the bushing bore 84 terminates in a counterbore 90, the juncturebetween the end wall of the latter and the bore 84 forming a fuelcontrol edge 91. The lower end of this counterbore 90 is closed by anupright cup 93 having a press fit therein and having its bottom endresting on the spacer 73 so that the walls of the cup are expanded intotight sealing relation with the walls of the counterbore when fuelpressure is built up within the bushing above the cup.

A hollow cylindrical cap 95 is inserted into the pump body 1 over theupper end of the bushing 33 and is provided with an external mountingflange 97 secured by cap screws to the pump body mounting flange 11. Theouter end 101 of the pump body bore is enlarged at 99 and a cooperatingexternal groove is provided in the cap member 95 to receive acompressible synthetic rubber sealing ring 103 which serves to preventfuel leakage between the pump body 1 and cap member 95. The inner end ofthe cap member 95 is counterbored as shown at 105 opposite the pump bodycounterbore 29 to loosely receive the bushing flange 39. As thesecounterbores 29 and 105 are at all times supplied with fuel from thereceiving space 40, they function as hydraulic stops limiting upward anddownward travel of the piston 49 and bushing 33 during pump operation.

Extending into the pump and having a close fit in the bore 84 of thebushing 33 is a cylindrical plunger 111. Camming means for thrustablysupporting and adjusting the plunger longitudinally of its axis isprovided in the end wall of the cap 95 by a central threaded aperture inwhich is fitted an externally threaded sleeve 107 having an arm 109fixed to its upper end whereby the sleeve may be rotated to adjustablyraise and lower the plunger relative to the cap. The upper portion ofthis plunger is journalled by the sleeve 107 whose lower end is inabutmeat with an external flange 112 on the plunger. A plunger rotatinglever 113 is suitably fixed to the plunger above the sleeve, and a nut115 threaded onto the upper end of the plunger serves to retain thelever 113, arm 109 and sleeve 107 in stacked abutting relation againstthe flange 112.

In order to prevent rotation of the bushing 33 upon rotation of theplunger 111 an axial slot 117 is provided in the upper end of thebushing portion 35 and a pin 119 is secured in the cap 95 and extendsinto the slot 117. The bore of the cap 95 is provided with an internalgroove in which a compressible synthetic rubber packing ring 120 isplaced to seal against the upper bush ing portion 35 and prevent fuelleakage into the upper end of the cap. An external fuel leakagereceiving groove 121 is provided on the inner end of the cap, and radialports 123 lead to this external groove 121 from an internal groove 122which is provided in the bore of the cap just below the packing ring120. The leakage ports 89 in the bushing 33 register with the internalgroove 122 in the cap when the piston 49 moves the bushing 33 into thepump body 1 to the end of the fuel discharge or injection stroke againstthe force of the plunger return spring 47. A radial port provided in thewall of the pump body 1 connects the groove 121 with the outer fuelreceiving space 17. With this arrangement any upward leakage of fuelbetween the plunger 111 and the bushing bore 84 above the fill ports 87is collected by the groove 89 and passes out through the ports 89 in thebushing, leakage ports 123 in the cap and port 125 in the body to thefuel space 17.

The space between the lower end of the plunger 111 and the cup 93 withinthe counterbore 90 constitutes a fuel pressure chamber. When the piston49 and bushing 33 are at the lower end of their reciprocatory stroke, asin Figure 1, fuel from the till ports 87 flows into this pressurechamber 130 by way of an annular groove 132 provided on the periphery ofthe plunger 111, which groove is connected with a downwardly extendingaxial plunger passage 134 by a transverse passage 136. As the piston andbushing are driven upwardly in the body 1 relative to the plunger 111,as the result of engine compression and combustion pressures acting onthe lower face 60 of the piston, the fill ports 87 are closed off by theupper edge of the groove 132 and the pressure of the fuel trapped belowthe plunger in the chamber 130 commences to build up. A metering grooveor recess 138 is provided on the periphery of the plunger below thegroove 132 to control the amount of this fuel pressure build-up and theescape of the fuel from the chamber 130 into either the tip port 85 orthe relief port 86. Since the recess 138 is not open to the axialpassage 134, the only means by which fuel may enter either of the ports85, 86 from the space 130 is by the recess 138 providing communicationbetween these ports and the counterbore 90. This does not occur untilthe control edge 91 moves above the lower extremity of the recess 138and one of the ports 85, 86 moves into partial registry overlappingrelation with the recess 138.

The structural relation of the recess 138 and annular groove 132 of theplunger to the fill ports 87, tip port 85, relief port 86 andcounterbore control edge 91 is best seen in Figure 2 which shows a 360development of the plunger 111 with the various bushing ports andcontrol edge superimposed thereon in broken outline. In Figure 2, thetip, relief and fill ports are in the positions indicated by thereference characters 85, 86 and 87 respectively, corresponding to thefull load or full fuel angular setting of the plunger (as controlled bythe lever 113 previously described). Also, the relative heights of theseports and the control edge 91 as indicated corresponds to that existingwhile the piston and bushing are at the lower end of their stroke andthe plunger is in its intermediate longitudinal setting relative to thestationary cap and pump body (as controlled by the regulating arm 109previously described). With the fill ports 87 thus registering With theplunger groove 132, filling of this groove, internai passages 134 and136 and the pressure chamber 130 can take place. With no change takingplace in the position of the plunger, it will be seen that as thebushing moves upwardly fuel pressure in the pressure chamber will bevented through the fill ports 87 until these ports reach the positionsindicated by reference characters 870 and the control edge 91 reachesthe level 910. Upon completion of this initial upward movement of thebushing further venting of the pressure chamber ceases, and continuedupward movement of the bushing results in fuel being trapped andcompressed in the pressure chamber. As the bushing continues its upwardmovement to the level corresponding to the control edge positionindicated by the reference numeral 911 further compression of fuel inthe pressure chamber ceases and injection begins by transfer of fuelfrom the pressure chamber via the recess 138 to the tip port from whichthe fuel is conducted to the injector nozzle. Injection continues withfurther upward movement of the bushing until the tip port reaches theposition indicated by reference character 85:- which occurssimultaneously with the diametrically opposite relief port reaching theposition 86:. Further upward movement of the bushing results in escapeof fuel from the pressure chamber through the relief port, and eventualstopping of the piston and plunger is effected by the hydraulic stopaction of the bushing flange entering the counterbore 195 as previouslydescribed with reference to Figure 1.

In the no load or no fuel position of the plunger (effected by rotatingthe plunger to the left as viewed in Figure 2), no compresion of fueltakes place during the upward stroke by reason of the relief port cominginto registry with the recess 133 simultaneously with closing of thefill ports 87. This is shown in Figure 2, wherein for convenience ofillustration, the bushing is assumed to rotate to the right relative tothe plunger in effecting the change from no fuel to full fuel positions.Accordingly, it will be seen that when the control edge has reached thelevel 911 the relief port will have simultaneously reached the positionindicated at 8611, the tip port having at the same time reached theposition indicated at 8511. In order that the start and end ofinjection, as determined by the closing off of the tip port and openingof the relief port respectively, may be varied between these limits ofno fuel and full fuel, the edges 138 and 138" are helically inclined tothe plunger axis. Further, with these edges 138 and 138" being parallel,as shown, the ending of fuel injection occurs simultaneously with therelief of pressure in the pressure chamber throughout the angularadjustment range of the plunger between full load and no load.

By adjustment of the plunger longitudinally of its axis, a longer orshorter fill period is effected, with the result that the bushing andpiston travel a greater distance before the start of pressure build-upin the pressure chamber and before injection commences. This variationin timing of the injection period may of course be accomplished withouteffecting any change in the total length of the fuel injection period,or any change in the degree of compression of the fuel prior to start ofinjection. The advantage gained is in enabling a proportioning of theinertia of the reciprocating mass to the length of its initial travelduring fill, thereby effecting both a further means of controlling theinjection pressure and the timing of the injection over the speed rangeof the engine. For this purpose, the control arm 109 (Figure 1) may bearranged for either manual adjustment or automatic adjustment by theengine governor in accordance with changes in speed.

Figure 4 shows a modified form of plunger 111' in which the recess 148is arranged to provide compression of the fuel in the pressure chamberin similar manner to that of Figure 2 except that the compression issubprior to start of injection, and hence is utilized only to controlinjection timing through control of speed of travel of the piston anddoes not utilize this fuel compression at the start of injection. Asshown in Figure 4 the recess 148 has a lower extremity or edge 149 whichextends circumferentially of the plunger and cooperates with the bushingcontrol edge 91 to control ending of fuel compression in the pressurechamber. The upper edge 152 of the recess is also circumferential andbetween it and the lower circumferential edge 149 is a land 53 having anupper circumferential edge 154 and a lower circumferential edge 155. Thecircumferential continuity of the land 153 is interrupted by a helicaledge 156 which extends upwardly from the edge to a short vertical edge157, and circumferentially opposite the vertical edge 157 the upper edge154 is relieved by a right angle notch formed by a vertical edge 158 anda circumferential edge 159.

The tip port 85, the relief port 86 and the control edge 91 of thebushing, as in the previous modification of Figure 2, are shown in theirfull fuel positions, as are also the fill ports 87, with the bushing atthe lower end of its stroke and the plunger in its intermediatel0ngitudinal position relative to the body and cap. During upward travelof the bushing the control edge first reaches the level indicated by thereference character 91c simultaneously with the fill ports reachingtheir positions indicated at 87. As the pressure chamber at this pointis still not in communication with the recess M8, further upward travelof the bushing results in compression of the fuel in the pressurechamber, which continues until the control edge reaches the level 9hcoincident with the lower edge 149. This occurs simultaneously with thetip port being closed by the circumferential edge 155 of the land 153,preventing any delivery of fuel to the nozzle. At this point the reliefport has not yet been covered by the helical edge 156, and duringfurther upward travel of the piston and bushing the fuel pressure in thepressure chamber is relieved by the relief port. This action continuesuntil the relief port reaches the position indicated at 861 at whichpoint the tip port is partially uncovered by the edge 159 and injectionthence commences and continues with further upward movement until therelief port reaches the position 86! at which it again becomes open tothe recess 148 and injection ceases.

At the no load" sequently relieved angular setting of the plunger, thetip port and relief port are in the positions indicated at 8511 and8611, respectively, when the bushing has travelled upwardly sufiicientlyfar for the helical edge 156 to effect closing of the relief port. Asthis also results in the circumferential edge 154 reopening the reliefport simultaneously with the opening of the tip port, no injection cantake place.

Intermediate these no load and full load angular settings of the plungerthe helical edge 156 provides a variable start of injection, while thecircumferential edge 154 effects a constant ending of injection. As inthe case of the Figure 2 modification, longitudinal adjustment of theplunger provides more or less initial or fill travel of the bushing andpiston, and thus the timing of the injection is controlled by shiftingthe fuel compression portion of the stroke toward the lower or upper endof the total stroke, with a resultant effect on the speed and inertia ofthe reciprocating parts. An advantage of this modification over that ofFigure 2 lies in the fact that by relieving the pressure built up in thepressure chamber during fuel compression prior to the start ofinjection, less opportunity exists for leakage of high pressure fuelinto the tip port such as might otherwise cause pre-injection in advanceof the desired start of injection.

The plunger 111" illustrated in Figure 3 is utilized in conjunction witha somewhat different form of bushing from that of bushing 33 previouslydescribed. Reference is therefore first made to Figure 6 which shows themodified bushing 33' (the view being taken at right angles to thesection of the assembly shown in Figure 1) having a second relief port160 extending transversely through one wall of the bushing lower portion37 to the bore 84 at a height slightly above the tip port 85 and itsdiametrically opposite relief port 86 (not shown). Diametricallyopposite the inner end of the relief port 160 is a blind extension 161thereof which serves as a transfer port in a manner to be hereinafterdescribed. The bushing incorporates the counterbore 90 the same as inthe case of the previously described bushing 33.

Referring now to Figure 3 the plunger 111" will be seen to have upperand lower recesses 165 and 166 respectively which are separate anddistinct from each other. As in the case of Figures 2 and 4 previouslydescribed, the various ports in the bushing as well as the control edge91 are indicated in their relative positions on the plunger developmentcorresponding to the positions they occupy with the piston and bushingat the lower end of their stroke, and with the plunger in its full fuelangular setting and intermediate longitudinal setting. From theserelative positions, upon upward travel of the bushing, the control edge91 reaches the level indicated at 91c simultaneously with the fill portsreaching their positions indicated at 87c, Where they are closed by theupper edge of the filling groove 132. Upon continued upward travel ofthe piston and bushing, start of injection occurs when the control edgereaches the level 911. The end of injection occurs when the tip portreaches the position indicated at 855 at which point the helical upperedge 167 of the lower recess 166 closes off the tip port. In themeantime, the transfer port 161 will have moved to the position 1615(tangent with the helical lower edge 168 of the upper recess 165). Theupper recess 165 having, up to this point, been out of communicationwith the lower recess 166, all the fuel displaced from the pressurechamber following the closure of the fill ports has been dischargedthrough the tip port. Since, as will be seen from Figure 3, the transferport in the position 1615 overlaps somewhat the helical upper edge 167of the lower recess 166 at the end of fuel injection, further upwardmovement of the bushing initially results in the transfer port partiallybridging both the recesses 165 and 166 during which fuel pressure in thelower recess 166 and the pressure chamber is relieved to the upperrecess and relief port 160. Also, prior to the tip port being uncoveredby the helical lower edge of the upper recess, the helical upper edge167 of the lower recess will cut off further transfer of fuel to theupper recess, and i e-trapping and re-compression of fuel in thepressure chamber will result to oppose further upward movement of thepiston and bushing and delay the relief of pressure in the tip passage.This delay of tip pressure relief has been found to have a beneficaleffect on engine fuel consumption by permitting the fuel pressure in thetip passage to effect its normal relief through the nozzle sprayopenings. The extent to which the relief of this tip pressure may bedelayed in the manner described is of course variable by varying thediameter of the transfer port and the height and inclination of theupper recess lower edge 168.

At the no fuel angular setting of tie plunger the tip port, transferhole and relief port are in the positions indicated at 85p, 161m and16011 respectively when the bushing has travelled upwardly to bring thecontrol edge to the level indicated at 911, whereupon former upwardmovement of the bushing results in an initial transfer of fuel from thelower to the upper recess, followed by retrapping and recompression offuel in the pressure chamber.

The bushing employed in the modification shown in Figure 5 is similar tothat of Figure 3, differing essentially only in that the axis of thetransfer port 161 and relief port 160 is below and at less than a rightangle about the longitudinal axis of the bushing to the axis of the tipport and relief port 86. Also, the counterbore does not have as great adepth as in the case of the bushings previously described and the upperend of this counterbore does not control the ending of fuel compressionin the pressure chamber. Instead, the beginning and end of fuelcompression in the compression chamber is controlled by the transferport and the upper extremity of a lower recess in the plunger, whichrecess is in con stant communication with the pressure chamber by way ofa transverse passage in the plunger connecting with the longitudinalinternal passage.

The Figure 5 modification provides for a primary injection preceding thetrapping and compression of fuel in the pressure chamber which, in turn,is followed by a secondary injection. Both the primary and secondaryinfaction periods have constant starting and variable ending timescontrollable by the angular setting of the plunger between full fuel andno fuel. As shown in Figure 5, the plunger 111' has its lower recess 173in constant communication, as mentioned, with the pressure chamber via atransverse passage 172 and the longitudinal passage 134, and has aseparate and distinct upper recess 174 by which the start and end of thesecondary injection period is controlled. The tip, transfer and tworelief ports are in their positions indicated at 85, 171, 86, and 170,respectively, when the bushing is at the bottom of its stroke and theplunger is in its intermediate longitudinal position and its angularposition corresponding to full fuel. Upon upward movement of the bushingthe cylindrical edge 175 of the lower recess closes off the relief holeprior to the closure of the tip port 85 by the circumferential upperedge 176 of the lower recess. Primary fuel injection thereupon beginsand continues until the tip port reaches the position indicated at 85.As this occurs prior to the transfer port uncovering the upper recess174, further upward travel of the bushing results in the trapping andcompression of fuel in the pressure chamber. It will be noted that atthis point the tip hole in the position 85 is also in partial registrywith the upper recess 174, and upon further upward travel of the bushingand uncovering of the upper recess by the transfer hole fuel will betransferred from the lower recess to the upper recess, resulting insimultaneous ending of fuel compression in the pressure chamber andstarting of a secondary injection. The secondary injection period willcontinue until the transfer port moves out of registry with the lowerrecess to the position indicated at 1715. Since at this time the bleedholes are in the positions indicated at 865 and 1705, respectively,relief of the pressure in the tip passage is delayed, this reliefeventually occurring after further upward travel of the bushing untilthe relief hole 170 uncovers the upper recess 174.

The lower recess circumferential edge has an inclined ramp portion 178which enables the start of primary injection to be varied by angularadjustment of the plunger about its axis.

When the plunger is rotated to cause the relief port 170 to assume theposition 170x at the end of the fuel filling period, no primaryinjection can take place since the tip port will then have been closedby the circumferential upper edge 176 of the lower recess. Such anangular adjustment of the plunger from the full load fuel setting isless than that necessary to cut off all fuel injection and does notaffect the timing or duration of the secondary fuel injection period.The circumferential edge 175 of the lower recess is connected to itscircum ferential upper edge 176 by a helical edge 177, and the ending ofthe secondary injection may be varied by angular adjustment of theplunger. Thus, initial angular adjustment of the plunger from its fullfuel" position shortens the duration of the primary fuel injectionperiod, by delaying the start thereof, and a further angular adjustmentof the plunger toward the no fuel position shortens the duration of thesecondary injection period by advancing the end thereof. This will beevident by noting that when the transfer port is in the positionindicated at 171n it has moved out of registry with the helical edge 177prior to uncovering the lower edge of the upper recess 174.

We claim:

1. In a fuel injector pump having two members in telescopic interfittingrelation forming a fuel compression space opposite one end of the innerof said members, means for reciprocating one of said members, stationaryguide means for said reciprocating member, camming means thrustablysupporting the other of said members on said stationary means, saidcamming means being movable relative to said other member and saidstationary means to vary the start of fuel compression relative to thelimits of the reciprocatory stroke of said reciprocating member, and acontrol member connected to said camming means for adjustable movementthereof during pump operation.

2. In a compression operated fuel injector pump, a reciprocably drivenmember forming a fuel compression cylinder, a stationary member slidablyguiding said driven member, a plunger supported by said stationarymember and extending into said cylinder, said plunger beinglongitudinally adjustable relative to said stationary member to vary thestart of fuel compression relative to the length of stroke of saiddriven member and also axially rotatable relative to said driven memberin any longitudinally adjusted position of said plunger to vary theeffective length of stroke of said driven member, and means foreffecting longitudinal adjustment of the plunger during pump operationincluding camming means thrustably interposed between the plunger andsaid stationary member and a control member connected to said cammingmeans for adjustable movement thereof relative to the plunger andstationary member.

3. In an engine compression pressure operated fuel injector pump, acompression pressure driven piston, a member movable with said pistonforming a fuel pumping cylinder and provided with a fuel deliverypassage having an entrance port in the bore of said cylinder, a plungeraxially rotatable in and slidably fitting the cylinder bore and havingsurfaces thereon controlling the opening and closing of said port duringreciprocation of said member in accordance with both the relativeangular and longitudinal positions of said plunger and member,stationary means reciprocably guiding said piston and member, and meansfor adjusting the longitudinal position of the plunger relative to saidstationary means including a sleeve threadedly engaging said stationarymeans and a control member connected to said sleeve for adjustablemovement thereof about its axis of threaded engagement with thestationary means, said plunger being journalled in said sleeve andhaving a flange and a nut in operative abutment with the opposite endsof the sleeve.

4. In an engine compression pressure operated fuel injector pump, acompression pressure actuated piston, a bushing extending longitudinallyof and carried by the piston, said bushing having a bore closed at oneend and forming a fuel pumping cylinder, removable closing means forsaid end including a spacer clamped between said end of the bushing andthe piston and a cup having its bottom wall abutting said spacer and itsside walls press fitted to the bore of the bushing.

5. In an engine compression pressure operated fuel injector pump, acompression pressure actuated piston having a bushing fixed to andextending longitudinally from one end thereof, said piston having anopening in its end opposite said bushing, a nozzle seated in saidopening, a spacer interposed between said nozzle and the adjacent end ofsaid bushing, an upright cup closely fitting the bore of said bushingand resting on said spacer, said bushing and spacer being provided withcommunicating fuel passages leading to said nozzle from the bore of saidbushing above said cup, a stationary body having a bore reciprocablyguiding said bushing, and 'a plunger thrustably supported by said bodyand slidably fitting said bushing, said plunger having a recess in theside thereof controlling the opening and closing of said passage duringreciprocation of the piston and bushing, said bushing bore, plunger andcup forming a closed chamber for trapping fuel in opposition to thecompression pressure actuation of said piston just prior to the openingof said passage by the recess.

6. In an engine compression pressure operated fuel injector pump,stationary means forming a fuel receiving chamber, reciprocating meansslidably guided by said stationary means and forming a fuel pressurechamber, spring means normally holding said reciprocating means at oneend of its stroke, a plunger thmstably supported by said stationarymeans and extending into said pressure chamber, said reciprocating meanshaving a bore slidably fitting said plunger and terminating in a controledge defining the upper end of said pressure chamber, a fuel nozzle,said bore having a tip port connected to said nozzle and relief and fillports connected to said receiving chamber, said plunger havingconnecting transverse and longitudinal passages, said longitudinalpassage being continuously open to said pressure chamber and saidtransverse passage being in registry with said fill port only during theinitial portion of the movement of the reciprocating means towards theopposite end of its stroke, said plunger also having an external recessproviding and controlling communication between said pressure chamberand said tip and relief ports respectively during successive portions offurther movement of the reciprocating means toward the opposite end ofits stroke, said recess having its lower extremity spaced below said tipand relief ports and above said control edge when said reciprocatingmeans reaches the end of its said initial movement, whereby during thefirst portion of its said further movement the reciprocating means isopposed both by said spring means and compression of fuel in saidpressure chamber by said plunger.

7. The invention defined in claim 6, wherein said recess has otherspaced apart extremities located to effect registry between said tipport and said recess and to prevent registry between said relief portand said recess when said control edge reaches said recess lowerextremity, whereby during the second portion of said further movementfuel is delivered from said pressure chamber to said nozzle via saidrecess and tip port.

8. The invention defined in claim 7, including plunger thrust supportingmeans adjustably movable longitudinally of the plunger axis relative tosaid stationary means for varying the extent of said initial movement ofthe reciprocating means.

9. The invention defined in claim 8, wherein said plunger is alsoangularly adjustable about its longitudinal axis relative to said thrustsupporting means and said bore and at least one of said other recessextremities is inclined to the plunger axis, whereby the extent of saidsecond portion of movement of the reciprocating means may be varied.

10. In an engine compression pressure operated fuel injector pump,stationary means forming a fuel receiving chamber, reciprocating meansslidably guided by said stationary means and forming a fuel pressurechamber, spring means normally holding said reciprocating means at oneend of its stroke, a plunger thrustably supported by said stationarymeans and extending into said pressure chamber, said reciprocating meanshaving a bore slidably fitting said plunger and terminating in a controledge defining the upper end of said pressure chamber, a fuel nozzle,said bore having a tip port connected to said nozzle and relief and fillports connected to said receiving chamber, said plunger havingconnecting transverse and longitudinal passages, said longitudinalpassage being continuously open to said pressure chamber and saidtransverse passage being in registry with said fill port only during theinitial portion of the movement of the reciprocating means towards theopposite end of its stroke, said plunger also having an external recessproviding and controlling communication between said pressure chamberand said tip and relief ports respectively during successive portions offurther movement of the reciprocating means toward the opposite end ofits stroke, said recess having its lower extremity spaced below said tipand relief ports and above said control edge when said reciprocatingmeans reaches the end of its said initial movement, whereby during thefirst portion of its said further movement the reciprocating means isopposed both by said spring means and compression of fuel in saidpressure chamber by said plunger, said recess having a land locatedintermediate its upper and lower extremities, said tip port being closedby said land and said relief port being in registry with the recessbelow said land when said control edge reaches said recess lowerextremity, whereby during the second portion of said further movementfuel is returned from said pressure chamber to said receiving chambervia said recess and relief port, said land having upper and lowerextremities successively effecting opening of said tip port, closing ofthe relief port and reopening of the relief port. whereby during thethird and fourth portions of said movement fuel is delivered from saidpressure chamber via the recess to first said tip port and then saidrelief port, respectively.

1 l. The invention defined in claim 10, including plunger thrustsupporting means adjustably movable longitudinally of the plunger axisrelative to said stationary means for varying the extent of said initialmovement of the reciprocating means.

12. The invention defined in claim ll, wherein said plunger is alsoangularly adjustable about its longitudinal axis relative to said thrustsupporting means and said bore and at least one of said land extremitiesis inclined to the plunger axis, whereby the duration of fuel deliveryto said tip port may be varied.

13. In an engine compression pressure operated fuel injector pump,stationary means forming a fuel receiving chamber, reciprocating meansslidably guided by said stationary means and forming a fuel pressurechamber, spring means normally holding said reciprocating means at oneend of its stroke, a plunger thrustably supported by said stationarymeans and extending into said pressure chamher, said reciprocating meanshaving a bore slidably fitting said plunger and terminating in a controledge defining the upper end of said pressure chamber, a fuel nozzle,said bore having a tip port connected to said nozzle, relief and fillports connected to said receiving chamber and a blind transfer port,said plunger having connecting transverse and longitudinal passages,said longitudinal passage being continuously open to said pressurechamber and said transverse passage being in registry with said fillport only during the initial portion of the movement of saidreciprocating means toward the opposite end of its stroke, said plungeralso having upper and lower external recesses providing and controllingcommunication between said pressure chamber and said tip and reliefports respectively, further movement of the reciprocating means towardthe opposite end of its stroke, said lower recess having its lowerextremity spaced below said tip port and above said control edge andsaid transfer and relief ports respectively being out of registry withsaid upper and lower recesses when said reciprocating means reaches theend of its said initial movement, whereby during the first portion ofits said further movement the reciprocating means is opposed both bysaid spring means and compression of fuel in said pressure chamber bysaid plunger, said lower and upper recesses having respective upper andlower extremities in spaced relation whereby during subsequent furtherup ward movement of the reciprocating means injection fuel delivery fromthe pressure chamber to the delivery port is discontinued in advance ofrelieving the fuel pressure in the tip port.

14. The invention defined in claim 13, wherein said transfer port isarranged to temporarily bridge both said recesses and thereby relievethe fuel pressure in said pressure chamber intermediate thediscontinuance of injection fuel delivery to and the relief of pressurein said tip port.

15. The invention defined in claim 14, including plunger thrustsupporting means adjustably movable longitudinally of the plunger axisrelative to said stationary means for varying the extent of said initialmovement of the reciprocating means.

16. The invention defined in claim 15, wherein said plunger is angularlyadjustable about its longitudinal axis relative to said thrustsupporting means and said bore and said upper extremity of said lowerrecess is inclined to the plunger axis, whereby the duration of fueldelivery to said tip port may be varied.

17. In an engine compression pressure operated fuel injector pump,stationary means forming a fuel receiving chamber, reciprocating meansslidably guided by said stationary means, spring means normally holdingsaid reciprocating means at the lower end of its stroke, a plungerthrustably supported by said stationary means, said reciprocating meanshaving a bore slidably receiving said plunger and forming a fuelpressure chamber thereunder, a fuel nozzle, said bore having a tip portconnected to said nozzle, relief and fill ports connected to saidreceiving chamber, and a blind transfer port, said plunger havingconnecting transverse and longitudinal passages, said longitudinalpassage being continuously open to said pressure chamber and saidtransverse passage being in communication with said fill port only whilethe reciprocating means is in the lower range of its stroke, saidplunger also having upper and lower external recesses providing andcontrolling communication between said pressure chamber and said tip andrelief ports respectively during further upward movement of thereciprocating means above said range, said plunger also having upper andlower external recesses formed in the periphery thereof below saidtransverse passage, said recesses and said tip, transfer and reliefports being arranged relative to each other that during upward movementof said reciprocating means above said range fuel is trapped in saidcompression chamber and then is released therefrom via said lower recessand transfer port to said tip port for injection through said nozzle,and following said injection said tip port remains out of communicationwith said relief port to delay relief of fuel injection pressure in saidnozzle pending a further upward movement of said reciprocating means.

18. In an engine compression pressure operated fuel injector pump,stationary means forming a fuel receiving chamber, reciprocating meansslidably guided by said stationary means, spring means normally holdingsaid reciprocating means at the lower end of its stroke, a plungerthrustably supported by said stationary means, said reciprocating meanshaving a bore slidably receiving said plunger and forming a fuelpressure chamber thereunder, a fuel nozzle, said bore having a tip portconnected to said nozzle, relief and fill ports connected to saidreceiving chamber, and a blind transfer port, said plunger havingconnecting transverse and longitudinal passages, said longitudinalpassage being continuously open to said pressure chamber and saidtransverse passage being in communication with said fill port only whilethe reciprocating means is in the lower range of its stroke, saidplunger also having upper and lower external recesses providing andcontrolling communication between said pressure chamber and said tip andrelief ports respectively during further upward movement of thereciprocating means above said range, said lower recess having a directconnecting passage to said longitudinal passage and being in and out ofregistry respectively with said tip and relief ports when said fill portmoves out of registry with said transverse passage whereby a primaryinjection of fuel is effected during the initial portion of said upwardmovement of said reciprocating means above said lower range, said lowerrecess having its upper extremity and said upper recess having its lowerextremity arranged to cause the tip port to move out of registry withsaid lower recess and into registry with said upper recess in advance ofsaid transfer and relief ports registering with the upper recess duringsaid upward movement of the reciprocating means, whereby following theperiod of said primary injection further upward movement of thereciprocating means is opposed both by said spring means and compressionof fuel in said pressure chamber by said plunger, and said transfer portto thereafter move sequentially into registry with said upper recess andout of registry with said lower recess while said tip port continues inregistry with the upper recess and in advance of said relief portregistering with said upper recess, whereby the period of said fuelcompression is followed first by a period of secondary fuel injectionand then a period of re-compression of fuel in said pressure chamber.

19. In an engine compression pressure operated fuel injector pump, acompression pressure driven piston, means forming a cylinder bore forsaid piston, a stationary body insertable into said bore opposite saidpiston, said piston having a reduced diameter portion reciprocablyguided in said body, spring means surrounding said portion and tendingto urge said piston away from said body, said reduced diameter portionand said bore defining an annular chamber into which engine air andcombustion gases escaping past said piston tend to create a backpressure opposing said piston, said piston having an external groove andan outspringing ring mounted in said groove for sealingly engaging saidbore, said groove having its side wall outwardly of said bore providedwith circumferentially spaced notches through which gases may escapefrom behind said ring to relieve said back pressure in said chamber.

20. In an engine compression pressure operated fuel injector pump, acompression pressure actuated piston, means forming a cylinder bore forsaid piston, a stationary body insertable into said bore opposite saidpiston, said piston having a reduced portion reciprocably guided in saidbody, a spring surrounding said portion and compressed between said bodyand said piston, said body having a counterbore facing said piston, aseat for said spring on said body closing the open end of saidcounterbore, and an annular ring of soft synthetic rubber compressed insaid counterbore by said spring seat, said ring having a plurality ofaxially spaced internal grooves, and inspringing metal rings mounted insaid grooves and sealingly embracing said reduced piston portion.

References Cited in the file of this patent UNITED STATES PATENTS1,047,341 Upton Dec. 17, 1912 1,541,944 Guerlay June 16, 1925 1,622,266Ake Mar. 29, 1927 2,518,901 King Aug. 15, 1950 2,576,451 Dickson Nov.27, 1951

